Energieffektivisering med fukthänsyn av ytterväggar på plankhus

Sammanfattning: Purpose: Villas built before 1960 represent around 45% of the dwelling in Sweden. Since the average U-value in their walls is around 0,5 W/m2K, there is a great concern to improve  these values. The Swedish government's goal is to reduce energy intensity in the country by 2020 by 20 % from 2008’s values. The aim of this study is to reach phase renovation proposals taking into account energy and moisture on houses consisting of standing shelves. With this, the authors wish to contribute and encourage renovation of existing villas, which in turn can lead to reduced energy consumption. Method: This work is based on a case study of a 1940’s wooden house located in Skillingaryd. Measurements and parameters have been taken in order to calculate the house's specific energy usage in the BV2 analysis program. Document analyses and interviews have been used to get a deeper knowledge of existing conditions, and to suggest ways to utilise the material that the market offers nowadays. This should serve the purpose of creating as energy-efficient phase resolution as possible. Result: The study shows that an outer wall of a massive wooden house should keep a U-value of 0,15 W/m2K to meet the specific energy consumption of 90 kWh/m2 and year, when the other house is additional insulated. The study presents two refurbishment proposals supported by interviewed experts in the insulation and consulting industry. The first option leaves large parts of the old facade untouched, adding new insulation layers of the desired thickness. The second option advises to tear away all old panels into the shelf frame, thus re-building with new materials. Both proposals address the issue of how the facade should be refurbished in order to make it moisture proof. They mostly solve the problem by refurbishing it outwards and by eventually placing a vapor barrier for a maximum of one third in of the insulation. This vapor barrier may or may not be a watershed according to the experts. Some think it is unnecessary when the plank is considered sufficiently diffusion-proof; some believe that it will help to identify where a possible condensation might occur in the wall.  Consequences: The study shows that by means of additional insulation, BBR 24 recommended values ​​can be achieved for an exterior wall while keeping the façade moisture proof. One strength the study shows that the two reported renovation proposals achieve the same end result, although the interference on the facade varies in size. Therefore the authors of the above study recommend to tear down the old facade and build a new control wall with a finishing facade disc. This is when you face a vapor barrier on the façade with a vapor barrier that is laid on the old baselayer of the roof. Then a new roof construction could be built up with roof beams, shavings and roof tiles. As a result, a windy, yet proportional, construction can be created.   Restrictions: The study assumes that the entire house would be refurbished in order for the specific energy use to be possible. Furthermore, the work is based of a shelf shelter located at a particular geographical site. Due to this, the study also offers suggestions on wooden facades only.  Keyword: Plank body, Phase renovation, Specific energy use, diffusion, convection, U-value, air density.